SUMMER 2013 VOLUME XLIX THE UARTERLY JOURNAL OF THE GEMOLOGICAL INSTITUTE OF AMERICA Contrast Patterns for Optimizing Brilliance in Colored Gemstone Faceting Fluorescence Produced by Common Optical Defects in Diamond Quick Reference Chart for Optical Defects in Diamond Nephrite Jade from the Italian Alps Summer 2013 VOLUME 49, No. 2 EDITORIAL 63 Integrating G&G with GIA’s Gemology Education Duncan Pay FEATURE ARTICLES 64 Optimizing Face-Up Appearance in Colored Gemstone Faceting pg. 65 Al Gilbertson Understanding the human visual system of interpreting contrast patterns can reveal facet-planning techniques to increase perceived brightness and optimize a gem’s appearance. 82 Fluorescence Produced by Optical Defects in Diamond: Measurement, Characterization, and Challenges Yun Luo and Christopher M. Breeding Studies of 3D fluorescence spectra from diamonds with different optical centers reveal that variations in UV lamp output can greatly affect observed fluorescence color and intensity. pg. 105 98 Nephrite Jade from Val Malenco, Italy: Review and Update Ilaria Adamo and Rosangela Bocchio Analysis of 21 rough and gem-quality samples offers an update on the composi- tion and properties of this pale green gem from the Italian Alps. NOTES AND NEW TECHNIQUES 107 Optical Defects in Diamond: A Quick Reference Chart James E. Shigley and Christopher M. Breeding A simple chart on optical defects in diamond, including those that produce coloration and fluorescence colors. pg. 117 REGULAR FEATURES 112 Thank You, Donors 113 Lab Notes Freshwater cultured pearls with damaged nacre • Calcium fluoride coating found on 13 “Fancy” pink diamonds • Diamond with fish-like inclusion • Large irradiated green-yellow diamond • Strong color zoning representing complex diamond growth environment • Very large single-crystal rough diamond • Unusual curved color zoning in emerald • Rare faceted neptunite 120 Gem News International Ancient tourmaline and beryl from Afghanistan • Orangy pink coated “soft coral” • Strands of tiny akoya keshi pearls • Green kyanite • Banded mimetite • Turquoise-rock crystal composite • Imitation Larimar Editorial Staff Editor-in-Chief Editorial Assistants Duncan Pay Brooke Goedert [email protected] Nathan Renfro gia.edu/gems-gemology Managing Editor Editors, Lab Notes Subscriptions Justin Hunter Thomas M. Moses Copies of the current issue may be purchased for [email protected] Shane F. McClure $29.95 plus shipping. Subscriptions are $79.99 for one year (4 issues) in the U.S. and $99.99 else - Editor Contributing Editors where. Canadian subscribers should add GST. Stuart D. Overlin James E. Shigley Discounts are available for group subscriptions, [email protected] GIA alumni, and current GIA students. For insti - Andy Lucas tutional rates, contact Customer Service. Technical Editors Editor-in-Chief Emeritus To purchase print subscriptions, visit store.gia.edu Tao Z. Hsu Alice S. Keller or contact Customer Service. [email protected] Customer Service Database Coverage Jennifer Stone-Sundberg Martha Erickson Gems & Gemology is abstracted in Thomson Associate Editor (760) 603-4502 Reuters products (Current Contents: Physical, [email protected] Chemical & Earth Sciences and Science Citation Claire Harlin Index— Expanded, including the Web of Knowl - [email protected] edge) and other databases. For a complete list of sources abstracting G&G , go to gia.edu/gems- gemology. Production Staff Manuscript Submissions Director, Content Development Photographer and Photo Editor Gems & Gemology welcomes the submission of Jan Iverson Robert Weldon articles on all aspects of the field. Please see the Guidelines for Authors at gia.edu/gandg or con - Creative Director Multimedia Specialists tact the Managing Editor. Letters on articles pub - Faizah Bhatti Joseph Kaus lished in Gems & Gemology are also welcome. 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Alan Jobbins Kenneth Scarratt other copying, reprint, or republication permis - Tokyo, Japan Caterham, UK Bangkok, Thailand sion, please contact the Managing Editor. Edward W. Boehm Mary L. Johnson James E. Shigley Gems & Gemology is published quarterly by the Chattanooga, Tennessee San Diego, California Carlsbad, California Gemological Institute of America, a nonprofit ed - ucational organization for the gem and jewelry in - James E. Butler Anthony R. Kampf Christopher P. Smith dustry. Washington, DC Los Angeles, California New York, New York Postmaster: Return undeliverable copies of Gems Alan T. Collins Robert E. Kane Wuyi Wang & Gemology to GIA, The Robert Mouawad London, UK Helena, Montana New York, New York Campus, 5345 Armada Drive, Carlsbad, CA 92008. John L. Emmett Lore Kiefert Christopher M. Welbourn Our Canadian goods and service registration num - Brush Prairie, Washington Lucerne, Switzerland Reading, UK ber is 126142892RT. Emmanuel Fritsch Thomas M. Moses Any opinions expressed in signed articles are un - Nantes, France New York, New York derstood to be opinions of the authors and not of the publisher. Jaroslav Hyršl Mark Newton Prague, Czech Republic Coventry, UK About the Cover The lead article in this issue examines the visual contrast patterns that optimize brightness in faceted gemstones. Brightness is superbly demonstrated by the gemstones shown on the cover, part of a collection of more than 100 tril - liant-cut stones on display at GIA Carlsbad. Clockwise from the top: 61.98 ct kunzite, 48.31 ct sphalerite, 9.67 ct grossular garnet, 7.71 ct zircon, 12.27 ct sphalerite, and 29.59 ct spessartine. Center: 25.15 ct fluorite. Collection cour - tesy of Roz and Gene Meieran; photo by Robert Weldon. Printing is by Allen Press, Lawrence, Kansas. GIA World Headquarters The Robert Mouawad Campus 5345 Armada Drive Carlsbad, CA 92008 USA © 2013 Gemological Institute of America All rights reserved. ISSN 0016-626X INTEGRATING G&G with GIA’s Gemology Education One of the things I’ve always wanted to do is create synergy between GIA’s gemology courses and Gems & Gemology. Many of the student assignments incorporate research from the journal, and adding G&G articles as references would provide support and validation for the infor- mation in our coursework. As we added video media to our eLearning courses, we featured interviews with many of GIA’s research scientists, some of whom were also G&G authors. Providing their articles to our students was a natural next step. In the past, I had discussed this idea with Alice Keller when she was editor-in-chief of G&G. Although everyone was willing, we had no practical way to achieve it at the time. Now that every issue is available free of charge on the redesigned GIA website at www.gia.edu, we can realize this ambition. Beginning with our Diamonds & Diamond Grading eLearning course, we’ll provide links at the end of every assignment to specially chosen G&G feature articles. Besides illuminating some of the source material for our coursework, links to supporting articles will provide a truly meaningful pathway into the resources on our new website. Students with inquiring minds will find many avenues of interest. Besides illuminating some of the source material For example, I believe a good number for our coursework, links to supporting G&G arti- of students would choose to explore cles will provide a truly meaningful pathway into the important G&G articles on the resources on our new website. colored diamond, diamond treatment, or diamond synthesis. Others might also download articles focused on mining, production, and the diamond supply chain, or read about the many famous gems examined or graded by GIA’s laboratory. This tie-in exposes the tremendous amount of important work that G&G authors—both internal and external to GIA—have done to enrich our collective knowledge on the many aspects of diamond, and makes it available to a wider, and younger, audience. We’ll also provide a short student study guide that explains the structure of a typical feature article and explains how to navigate one. In time, we’ll add similar links to relevant G&G articles in our other gemology courses. Let me take this opportunity to thank all our current G&G print subscribers and online users. I hope to welcome many more of you in the near future. Duncan Pay | Editor-in-Chief | [email protected] EDITORIAL GEMS & GEMOLOGY SUMMER 2013 63 FEATURE ARTICLES OPTIMIZING FACE-UP APPEARANCE IN COLORED GEMSTONE FACETING Al Gilbertson The human visual system interprets visual cues to perceive different intensities of brightness. Patterns of light and dark contrast create impressions of brightness in faceted gemstones. These patterns generally remain coherent in the viewer’s eye when the gemstone is tilted or rotated. Using computer-generated color-coded contrast maps in facet planning can improve apparent brightness, optimizing a gemstone’s appearance. here are many challenges in choosing a facet will lead to a faceted gemstone with maximum appeal arrangement that optimizes a colored stone’s given the constraints of the material at hand. This T face-up appearance. What contributes to an at- paper focuses on gems with colors that are not easily tractive appearance? In the field of cognitive science, weakened by pronounced brightness or darkness, sim- experts have identified rules that govern our percep- ilar to the medium range of tone and strong saturation tion of visual cues such as line, color, form, brightness, found in peridot (figure 1).